Favorite Form (3.5e Feat)

From D&D Wiki

In addition to your regular form, you have one specific form that you favorite among all the others...

Prerequisite: Alternate Form ability, Altered Form Familiarity

Benefit: Choose one alternate form with one specific appearance as your favorite.

Special: In conjunction with Partial Transformation, you can morph certain aspects (such as your tough dragon's scales for natural armor AC bonuses) while in your Favorite Form, without it showing through (something that could prove useful when subterfuge is required).